57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
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"""Compare finger-bone REST rotations between GLB skeletons.
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First GLB is the reference; each other is reported as per-bone angle deviation (degrees).
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usage: rest_deviation.py canonical.glb other.glb [more.glb ...]
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"""
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import json, struct, sys, math
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from pathlib import Path
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FING = ("thumb", "index", "middle", "ring", "pinky")
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def read_gltf(path):
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d = Path(path).read_bytes()
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jlen = struct.unpack_from("<I", d, 12)[0]
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return json.loads(d[20:20 + jlen].decode("utf-8"))
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def rests(path):
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g = read_gltf(path)
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out = {}
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for nd in g["nodes"]:
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n = nd.get("name", "")
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if any(t in n.lower() for t in FING):
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out[n] = nd.get("rotation", [0, 0, 0, 1])
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return out
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def angle_between(a, b):
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"""Geodesic angle (deg) between two unit quaternions, sign-insensitive."""
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d = abs(sum(x * y for x, y in zip(a, b)))
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d = max(-1.0, min(1.0, d))
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return math.degrees(2 * math.acos(d))
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ref_path = sys.argv[1]
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ref = rests(ref_path)
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print(f"reference: {Path(ref_path).name} ({len(ref)} finger bones)")
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for p in sys.argv[2:]:
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other = rests(p)
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print(f"\n== {Path(p).name} == {len(other)} finger bones")
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missing = sorted(set(ref) - set(other))
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extra = sorted(set(other) - set(ref))
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if missing:
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print(f" MISSING vs ref ({len(missing)}): {', '.join(missing)}")
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if extra:
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print(f" EXTRA vs ref ({len(extra)}): {', '.join(extra)}")
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devs = []
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for n in sorted(set(ref) & set(other)):
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devs.append((angle_between(ref[n], other[n]), n))
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devs.sort(reverse=True)
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if not devs:
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continue
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over = [d for d in devs if d[0] > 1.0]
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print(f" shared {len(devs)} | deviating >1deg: {len(over)} | max {devs[0][0]:.1f}deg ({devs[0][1]})")
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for d, n in devs[:12]:
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print(f" {n:24s} {d:6.1f}deg")
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